1. Field of the Invention
This invention relates to a disk cartridge whose hard jacket is provided with an openable and closeable shutter that accommodates a disc-shaped recording medium.
2. Description of the Prior Art
Conventional media for magnetic recording use a magnetic disk to provide compatibility and accessibility. To prevent the magnetic disk from being damaged and its recording surface from being soiled during insertion and ejection of the magnetic disk in a recording and reproducing apparatus, a disk cartridge is proposed of the type wherein the magnetic disk is rotatably accommodated in a plastic hard jacket formed with a head window and this head window is covered with an open/close-able shutter. This type of disk cartridge is generally called a 3.5 inch floppy disk cartridge and widely used nowadays.
Recently, in view of a demand for large capacity of recording, attention has been paid to magneto-optical recording instead of magnetic recording. Magneto-optical recording media are used in the form of a disk of magneto-optical material. To protect the magneto-optical disk and prevent its recording surface from being soiled, the magneto-optical disk is accommodated in a disk cartridge having an openable and closeable shutter, as is the case of the foregoing magnetic disk.
FIGS. 13 and 14 are schematic diagrams showing an example of the magneto-optical disk cartridge, whose shutter is in the closed state in FIG. 13 and in the open state in FIG. 14.
A magneto-optical disk cartridge A (hereinafter referred to as the cartridge A) accommodates a magneto-optical disk B. On the side of a front edge H of the cartridge A there is formed a recess D in which a shutter C is seated. An opening E is formed in a central portion of the recess D. The shutter C is supported by a guide mechanism (not shown) so as to slide in the recess D laterally in the drawing, and is always urged by a shutter return spring F toward the closed position shown in FIG. 13. The shutter C is formed with an opening G which, when the shutter moves to the open position shown in FIG. 14 comes into alignment with the opening E. Therefore, when the shutter C stands at the closed position shown in FIG. 13 a recording surface of the magneto-optical disk B is covered with the shutter C, whereas when the shutter C moves to the open position shown in FIG. 14 the opening G comes into alignment with the opening E so that the recording surface of the magneto-optical B is exposed.
Formed at the front edge H of the cartridge A is a notch I for locking of the shutter C at the open position.
An example of a shutter operating unit for automatically opening and closing the shutter C of the cartridge A will be described with reference to FIGS. 15 and 16. In these drawings, the solid lines illustrate the positions of individual parts when the shutter C is in the completely open state, whereas the two-dot chain lines illustrate the positions of individual parts when the shutter C is in the completely closed state.
A holder J in which the cartridge A is inserted is lifted by a lifting mechanism (not shown) between the depressed position where it approaches a main chassis K to permit recording and reproducing with respect to the cartridge A and the raised position where it separates from the main chassis K to permit insertion/ejection of the cartridge A. A rotary lever L, rotatable in response to the insertion/ejection of the cartridge A, is rotatably supported at one end via a rotary shaft M by the holder J. Rotary lever urged clockwise by a spring N, and provided at the other end with an engage pin P which is engageable with the shutter C of the cartridge A. A cartridge eject lever Q is rotatably supported at one end via a rotary shaft R by the main chassis K, urged counterclockwise by a spring S, and provided at the other end with a cartridge eject pin T. As will be described later, this cartridge eject lever Q upon its rotation actuates the foregoing lifting mechanism and ejects the cartridge A from inside the holder J.
The operation of insertion/ejection of the cartridge A with respect to the shutter operating unit will be described.
When the cartridge A is gradually inserted into the holder J, the engage pin P of the rotary lever L comes into contact with the front edge of the cartridge A and one side edge C.sub.1 of the shutter C at the two-dot chain line position. When the cartridge A is further inserted, the engage pin P is pushed by the front edge H of the cartridge A, the rotary lever L is rotated counterclockwise with the spring N elongated, the side edge C.sub.1 of the shutter C is pushed by the engage pin P, and the shutter C is moved leftward in the drawing in opposition to the shutter return spring F. At the solid line position, the engage pin P completely fits in the notch I of the cartridge A, so that the shutter C is locked in the open position.
On the other hand, the eject pin T of the cartridge eject lever Q is pushed by the front edge H of the cartridge A, and the eject lever Q is rotated clockwise in opposition to the spring S and locked at the solid line position by a lock mechanism (not shown). The rotation of the eject lever Q actuates the lifting mechanism, so that the holder J is moved from the raised position to the depressed position. Here, as shown in FIG. 16 in greater detail, the operation of rotation of the cartridge eject lever Q is caused when the cartridge A is inserted after the complete opening of the shutter C subsequent to the halfway falling of the engage pin P in the notch I, or when the cartridge A is inserted a distance l (l=d-r) from the one-dot chain line position up to the solid line position after the opening of the shutter C, where r is the radius of the engage pin P and d is the depth of the notch L. To make the distance l sufficiently long, the depth d of the notch L is set to about 2.5 times the radius r of the engage pin P.
At the solid line position, the engage pin P receives the urging force n of the spring N of the rotary lever L and the returning force f of the shutter return spring F transferred from the side edge C.sub.1 of the shutter C, thus is pressed against a side wall I.sub.1 of the notch I.
The operation of ejection of the cartridge A is caused by releasing the engage pin P from the notch I. Specifically, in FIG. 16, this operation of ejection is rendered possible by pushing out the cartridge A more than the distance l in the direction of ejection in opposition to the frictional force between the engage pin P and the side wall I.sub.1 of the notch I that results from the urging force n of the spring N and the frictional force between the engage pin P, the side edge C.sub.1 of the shutter C, and the side wall I.sub.1 of the notch I that results from the returning force f of the shutter return spring F. That is, upon releasing the locking of the eject lever Q, the eject lever Q is rotated counterclockwise by the urging force of the spring S, so that the eject pin T pushes the front edge h of the cartridge A in the direction of ejection. When the cartridge A moves past the one-dot chain line position because of the foregoing pushing, the engage pin P is released from the notch I to permit rotation of the rotary lever L, so that in response to the rotation of the eject lever Q, the holder J is moved to the raised position, and by the returning force of the shutter return spring F and the urging force of the spring N coupled to the rotary lever L, the cartridge A is ejected from the holder J.
In the foregoing cartridge A, when the shutter C is locked at the open position, the spring N of the rotary lever L is the longest and the returning force f of the shutter return spring F is the largest. Thus the engage pin P of the shutter operating unit is pressed against the side wall I.sub.1 of the notch I with strong force. Therefore, to release the engage pin P from the notch I thereby to eject the cartridge A from the holder J, the spring S of the eject lever Q must be made so strong that the cartridge A can be pushed in the direction of ejection over more than the foregoing distance l with fairly strong force. However, where the spring S is made strong as described above, to rotate the eject lever Q in opposition to the urging force of the spring S at the time of insertion of the cartridge A, the cartridge A must be inserted into the holder J with fairly strong force; thus, operation of the cartridge A has an unpleasant feel.